Crystal Bridge

Magical force coalesces into physical form, taking the shape of a clear crystal bridge. The bridge connects any point within range with a point right in front of the casters feet. The bridge can not curve, can at maximum raise/fall a 45 degree angle; it can be from 5 to 20 feet wide.

You can designate one creature per spell level. A creature who attacks a designated target, while that target is on the bridge, must succeed on a wisdom saving throw. On a success the spell has no effect on the attack, but on a failure, the attacker must chose a target not affected by this spell instead, or the attack falters.

Creatures hit by the bridge as it is forming are pushed either below or above the bridge. 

The bridge can be dispelled, but is impervious to damage and provides full cover against attacks that have to go through the bridge. A Disintegrate spell destroys a 20 ft area of the bridge.

If concentration on this spell is broken, the protective effect ends immediately. The bridge then starts evaporating from the center, with 10 feet of bridge vanishing in both directions per round on the start of the casters turn.

If the spell is cast at a higher level, the range of the spell increases by 20 ft per spell level, in addition to more creatures being targetable by the protection.

 "I go where none has gone before"
- Aerlar Mindathis, also known as Damian Althiser